Supernus Pharmaceuticals (SUPN) shares spike 24%, adding to an 8% gain in regular trading, after the company announces the FDA has approved Orenitram extended-release tablets for the treatment of pulmonary arterial hypertension in WHO Group I patients to improve exercise capacity.

The news broke last week, but it appears that investors have had in their memory that Supernus has a development/licensing agreement for the drug with United Therapeutics jolted by the PR.

Supernus developed the formulation under an agreement with United Therapeutics (UTHR+30.4%), whose shares rocketed when the approval was announced earlier today. United will pay Supernus certain milestone fees and royalties on global product sales.

United Therapeutics (UTHR) has received a subpoena from the Department of Health & Human Services requesting documents related to the company's marketing of three treatments for pulmonary arterial hypertension (PAH).

The drugs involved, which are United Therapeutics' Remodulin injection, its Tyvaso inhalation solution and its Adcirca tablets, are the firm's only therapies that have received FDA approval.

United Therapeutics (UTHR-3%) slides after its Q1 EPS results missed Street expectations earlier today. Revenue increased by nearly $41M over the prior year the period, with growth in product revenues reflecting the continuing increase in the number of patients being treated, but expenses in both R&D and SG&A pressured bottom line performance.

United Therapeutics Corp is a biotechnology company. The Company is engaged in thedevelopment and commercialization of products to address the unmet medical needs of patients with chronic and life-threatening conditions.